What is ILD? ILD is the short form for Initial Load Deflection. This is just another way of saying initial softness or how the surface feels.  When you push down on memory foam, that initial feel is ILD.
ILD is a standard measurement, which is: How much pressure is required to compress memory foam by 25%.

Most memory foam products have similar ILD ratings, which means that they will all feel similar to the initial touch but that is not all that needs to be considered. An ILD rating of 11-15 is considered optimum for sleep products. In addition to the conformability of the memory foam what we also need is the ability of the foam to support without bottoming out. If the foam bottoms out you will feel pressure points.

In order to get the support that you need you need to look at the density. Density is the amount of “polymer “ that is in the foam. This is measured as the weight of a cubic foot of foam. Higher density means more support.

ILD and Density are two different properties of memory foam that can be controlled individually. You can have firm foam that’s low density, soft foam that’s high density and anything in between.  There is no direct relationship between ILD (feel) and Density (support).

A memory foam product with an ILD of between 11-15 with a high density in the range of 5lbs. will provide you with good feel, required support and longevity.